Nowadays, a polarizing plate is generally used to filter natural light in order to produce linearly polarized light.
However, since the polarizing plate will absorb the component in incident light that cannot be transmitted, its light energy utilization ratio may be only 50% at most in theory, and generally only about 40% in practice, which leads to a great energy waste.
Furthermore, an existing polarizing plate cannot control the direction of transmitted light, and thus is not applicable to some situations that require parallel linearly polarized light (such as, a specific light modulator, a display apparatus, etc.).